In U.S. Pat. Nos. 8,563,071 and 8,691,318 and U.S. patent application Ser. No. 13/879,418 filed Aug. 1, 2013 (US Patent Publication No. 2013-0316069 published Nov. 28, 2013) (“S701”), assigned to the assignee hereof and the disclosures of which are incorporated herein by reference, there are described procedures for the preparation of protein products with excellent solubility, heat stability and clarity in low pH solutions as well as a clean flavour, without beany notes.
In U.S. patent application Ser. No. 13/924,860 filed Jun. 24, 2013 (US Patent Publication No. 2014-0010940 published Jan. 9, 2014) (“S701N2”) and in U.S. patent application Ser. No. 12/975,805 filed Dec. 22, 2010 (US Patent Publication No. US 2011-0165314 published Jul. 7, 2011) and Ser. No. 13/518,217 filed Sep. 5, 2012 (US Patent Publication No. US 2012-0322980), assigned to the assignee hereof and the disclosures of which are incorporated herein by reference, there are described the provision of neutral or near neutral pH forms of the soy protein products described above. These products, with their clean taste, are useful for food compositions having a neutral or near neutral pH. Although solubility is still desirable, food applications at neutral or near neutral pH are typically not transparent and so complete solubility and clarity in water are not necessarily a requirement.
In the procedures described in the aforementioned U.S. Pat. Nos. 8,563,071 and 8,691,318 and U.S. patent application Ser. Nos. 13/879,418, 13/924,860, 12/975,805 and 13/518,217, protein extraction is effected with calcium salt solution. The calcium salt solution assists in solubilisation of protein from the protein source while separating it from phytic acid, which is precipitated and remains with the residual protein source. The protein extract solution is optionally diluted with water and adjusted in pH to about 1.5 to about 4.4 to provide a clear, acidified protein solution. While not wishing to be bound by any particular theory, it is thought that the clean flavour of the soy protein products obtained by these procedures is promoted by the low pH treatment of the sample, preferably in combination with optional subsequent membrane processing steps.
One potential concern with the procedures described in the aforementioned U.S. Pat. Nos. 8,563,071 and 8,691,318 and U.S. patent application Ser. Nos. 13/879,418, 13/924,860, 12/975,805 and 13/518,217 is the quantity of calcium salt required to effect the protein extraction step and the costs and issues of the quantity of salt entering the process as well as the recovery or disposal of calcium salts in the waste streams of the process. A reduction or elimination of calcium salt could result in significant savings in the cost of processing and production of the protein products.